def matches(left, right):
    left_brackets = "([{"
    right_brackets = ")]}"
    return left_brackets.index(left) == right_brackets.index(right)


a = 'abc'
print(a.index('a'))

my_list = []
if not my_list:
    print("列表为空")
else:
    print("列表不为空")

# print([1, 2, 3] - [1, 2])


a = [1, 2, 3, 3, 3]
for i in a:
    print(a.count(i))
